EXAMINATION  OF  THE  SULPHATE  OF  QUINIA. 
401 
placed  under  the  bell  glass  to  cool.  In  three  hours  the  whole 
were  put  upon  the  balance  and  weighed.  The  net  yield  of  fused 
precipitate  was  4-0702  gram. 
Experiment  No.  5. 
Portion  B,  of  the  last  experiment,  was  dissolved  in  fifty 
grains  of  distilled  water,  acidulated  with  18  drops  of  hydro- 
chloric acid.  In  connection  with  this  solution,  it  is,  perhaps, 
worth  while  to  mention  a  convenient  method  for  removing  in- 
soluble particles,  that  are  frequently  found  in  such  solutions, 
without  the  trouble  and  loss  of  filtration.  The  solution  was  stirred 
around  until  it  was  in  a  rapid  whirl,  and  the  glass  stirring  rod 
removed  and  rinsed  off  into  the  solution  with  a  few  drops  of  dis- 
tilled water  from  the  wash  bottle,  and  the  square  ground  end 
carefully  dried.  A  small  pellet  of  wax,  weighing  -1562  gram., 
was  then  made  to  adhere  to  the  dry  flat  end  of  the  rod,  in  the 
form  of  a  flattened  sphere.  On  examining  the  solution  then,  the 
whirling  motion  was  found  to  have  nearly  ceased,  and  the  particles 
all  collected  into  a  little  hillock  in  the  centre  of  the  beaker.  The 
armed  stirring  rod  was  then  carefully  passed  straight  down  upon 
the  particles,  with  a  force  just  sufficient  to  imbed  them  in  the 
wax,  and  then  removed  and  again  rinsed  off  into  the  solution 
with  a  few  drops  of  water.  The  wax  pellet,  containing  the 
particles,  was  then  carefully  removed,  dried,  and  replaced  in  the 
balance ;  and  enough  of  the  original  salt  was  placed  upon  the 
•1  gram,  plantinum  weight  of  the  opposite  pan,  to  restore  the 
equipoise.  This  salt  was  then  washed  off  into  the  solution  and 
dissolved. 
Solution  of  chloride  of  barium  was  then  added  in  excess,  and 
the  whole  allowed  to  stand  closely  covered,  for  twenty-four  hours. 
The  supernatant  liquor  was  then  drawn  off  by  a  pipette,  and  re- 
placed by  distilled  water,  when  the  whole  was  well  stirred  and 
again  allowed  to  stand  twenty-four  hours  and  decanted.  Dupli- 
cate filters,  about  21  inches  in  diameter,  were  then  cut  of  exactly 
the  same  size,  from  the  same  piece  of  paper,  and  upon  one  of 
these  the  precipitate  was  collected,  washed  with  50  gram,  of 
water  and  drained.  The  empty  duplicate  filter  was  then  perfect- 
ly burned  in  a  weighed  crucible,  cooled  over  sulphuric  acid,  and 
then  found  to  yield  -0014  gram,  of  ash.    The  filter  and  pre- 
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